Production painting operations generally utilize a paint spray booth designed to contain paint overspray. In conventional paint spray booths, water flowing along a wall of the paint booth forms a backdrop against which the water entrains oversprayed particles from the airflow within the paint booth. This mixture of water and paint particles cannot be disposed of pursuant to environmental regulations and there is a need to conserve water.
Therefore, various apparatus have been conceived in which paint particles within the water are agglomerated in a separating tank by the introduction of chemicals to the water and paint particle mixture. Agglomerated paint particles rise and float on the surface of the water in the separating tank, forming a sludge thereon which is periodically skimmed off, collected and disposed of. Treated water, with the paint particles removed, is recirculated to the paint booth.
Three such apparatus are disclosed in U.S. Pat. Nos. 4,610,785; 4,470,905; and 4,432,870.
U.S. Pat. No. 4,610,785 discloses a sludge separation tank divided into two regions and having a baffle disposed in the separation tank adjacent the outlet of the pump for directing sludge entering the separation tank toward the surface of the liquid.
U.S. Pat. No. 4,470,905 discloses a sludge separation tank having an inlet opening in the bottom of the tank directing a mixture of paint particles in the water carrier upwardly and a vertical upstanding first wall dividing the tank into an inlet and an outlet section.
U.S. Pat. No. 4,432,870 discloses a sludge separation tank having a water inlet at water level and a water return opening below the surface level. The tank includes liquid circulating jets for recirculating paint particles settling on the tank bottom.
All of the aforesaid apparatus include restrictive flow regions within the separation tanks that inhibit the efficiency of said apparatus allowing some paint particles to settle to the bottom of the tanks. Furthermore, said apparatus create regions of stagnated flow or dead spots on the surface of the water whereby periodic manual sludge removal or cleaning of the tank is required.